Denitration system and denitration method for tail gas of ammonia fuel engine

Abstract

The invention relates to the technical field of ship engine tail gas treatment, and discloses a denitration system and a denitration method for ammonia fuel engine tail gas. The denitration system comprises an ammonia fuel engine and a denitration device, the liquid ammonia fuel supply device is connected with the ammonia fuel engine through a supply pipeline and is used for supplying ammonia fuel to the ammonia fuel engine; a gas inlet of the ammonia gas buffer tank is connected with the supply pipeline, and the ammonia gas buffer tank is used for collecting unburned ammonia gas generated in the supply pipeline; the ammonia water preparation device is connected with a gas outlet of the ammonia gas buffer tank and an outlet of the liquid ammonia fuel supply device; and the tail gas denitration device is connected with an outlet of the ammonia water preparation device and an exhaust port of the ammonia fuel engine. The liquid ammonia fuel and the fresh water are mixed to prepare the ammonia water, and the prepared ammonia water is used for subsequent nitrogen oxide reduction of the tail gas of the ammonia fuel engine, so that the problem that the unburned ammonia gas is difficult to treat can be solved, construction of other reducing agent (such as urea) bins can be omitted, and occupation of the reducing agent on the ship space is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ship engine exhaust gas treatment, and particularly relates to a denitration system and a denitration method for the exhaust gas of an ammonia fuel engine. Background Art

[0002] Since ammonia fuel ship engines can reduce carbon dioxide emissions, the application technology of ship ammonia fuel is currently the key development direction of ship power.

[0003] Since the emission products of ammonia fuel ship engines contain more nitrogen oxides, tail gas denitration devices are usually equipped on ships at present. In the tail gas denitration device, nitrogen oxides are reduced to nitrogen and water by using a reducing agent (for example: urea) and a catalyst, thereby greatly reducing the emission of nitrogen oxides. However, since ammonia fuel ship engines need to operate continuously for a long time, it is necessary to reserve a sufficient amount of reducing agent on the ship in advance. However, storing a large amount of reducing agent in advance will not only occupy the limited space on the ship, but also increase the upfront procurement cost. Summary of the Invention

[0004] In view of this, the present invention provides a denitration system and a denitration method for the exhaust gas of an ammonia fuel engine to solve the problems mentioned in the background art.

[0005] In a first aspect, the present invention provides an ammonia fuel engine exhaust gas denitration system, comprising:

[0006] An ammonia fuel engine;

[0007] A liquid ammonia fuel supply device, connected to the ammonia fuel engine through a supply pipeline, for supplying ammonia fuel to the ammonia fuel engine;

[0008] An ammonia gas buffer tank, the inlet of which is connected to the supply pipeline, for collecting unburned ammonia gas generated in the supply pipeline;

[0009] An ammonia water preparation device, connected to the outlet of the ammonia gas buffer tank and the outlet of the liquid ammonia fuel supply device;

[0010] A tail gas denitration device, connected to the outlet of the ammonia water preparation device and the exhaust port of the ammonia fuel engine.

[0011] Beneficial effects: The present invention utilizes an ammonia buffer tank to collect the unburned ammonia generated in the supply pipeline. This not only avoids the direct emission of ammonia, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operating cost. Secondly, the unburned ammonia is transported to the ammonia water preparation device, converting the ammonia that might otherwise be wasted or difficult to handle into ammonia water that is easier to store, transport, and use. The ammonia water is relatively stable in state, reducing the safety risks of subsequent operations. Moreover, a part of the liquid ammonia in the liquid ammonia fuel supply device is directly transported to the ammonia water preparation device, enabling operators to flexibly adjust the preparation concentration of ammonia water according to actual needs, ensuring the purification effect of ammonia water on the exhaust gas of the ammonia fuel engine. Finally, the prepared ammonia water is transported to the tail gas denitrification device to treat the exhaust gas of the ammonia fuel engine, effectively removing harmful components such as nitrogen oxides in the exhaust gas. In addition, since ammonia water can replace the conventional reducing agent urea, the construction of the urea storage on the ship can also be cancelled, reducing the occupation of ship space by the reducing agent.

[0012] In an alternative embodiment, the ammonia water preparation device includes a washing cabinet, an ammonia water preparation equipment, and a fresh water supply device connected to the washing cabinet and the ammonia water preparation equipment. The washing cabinet is connected to the outlet of the ammonia buffer tank. The outlet of the washing cabinet and the outlet of the liquid ammonia fuel supply device are respectively connected to the inlet of the ammonia water preparation equipment. The outlet of the ammonia water preparation equipment is connected to the tail gas denitrification device.

[0013] Beneficial effects: The present invention transports both ammonia and fresh water into the washing cabinet, enabling the ammonia to react with the fresh water to obtain ammonia water. Compared with ammonia, when ammonia is converted into ammonia water, its state is relatively more stable, so it can be more conveniently transported and stored. In addition, transporting fresh water and liquid nitrogen to the ammonia water preparation equipment can increase the final preparation concentration of ammonia water, avoiding the situation where only unburned ammonia is used to prepare ammonia water and unable to meet the reduction requirements of the exhaust gas of the ammonia fuel engine.

[0014] In an alternative embodiment, a reflux port is provided on the bottom and / or side wall of the washing cabinet, and a spray port is provided on the top of the washing cabinet. The reflux port is connected to the spray port through a reflux pipeline and a reflux pump provided on the reflux pipeline.

[0015] Beneficial effects: By providing a reflux port on the bottom and / or side wall of the washing cabinet, a spray port on the top, and connecting the two with a reflux pipeline and a reflux pump, the present invention can make the liquid in the washing cabinet form a circulation. This circulation process can enable ammonia to contact and react with fresh water more fully, improving the concentration of the prepared ammonia water.

[0016] In an alternative embodiment, the fresh water supply device includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is connected to the washing cabinet and the ammonia water preparation device respectively through a fresh water delivery pipeline.

[0017] Advantageous effects: By providing a fresh water pump in the present invention, operators can flexibly adjust the amount of fresh water delivered to the washing cabinet and the ammonia water preparation device. Specifically, when it is necessary to increase the ammonia water concentration, the fresh water delivery volume is reduced; if it is necessary to dilute the ammonia water, the delivery volume is increased to ensure that the ammonia water concentration is always maintained within a suitable range.

[0018] In an alternative embodiment, first spray heads are provided inside both the washing cabinet and the ammonia water preparation device. The first spray heads are in communication with the fresh water delivery pipeline; a first regulating valve and a first flow meter are also provided on the fresh water delivery pipeline.

[0019] Advantageous effects: By providing first spray heads inside the washing cabinet and the ammonia water preparation device, fresh water can be evenly dispersed in the washing cabinet and the ammonia water preparation device in the form of spray, increasing the contact area between fresh water and ammonia gas or liquid ammonia, promoting the reaction rate between the two, and improving the production efficiency and quality of ammonia water. By providing a first regulating valve and a first flow meter on the fresh water delivery pipeline, precise quantitative control and dynamic adjustment of fresh water can be achieved, which helps to maintain the stability of the ammonia water concentration in the washing cabinet and ensure that the ammonia water quality meets the working requirements of the tail gas denitration device.

[0020] In an alternative embodiment, an ammonia water concentration detection device and a liquid level detection device are provided on the ammonia water preparation device. The ammonia water concentration detection device is used to detect the ammonia water concentration in the ammonia water preparation device; the liquid level detection device is used to detect the height of the ammonia water liquid level in the ammonia water preparation device.

[0021] Advantageous effects: By providing an ammonia water concentration detection device on the ammonia water preparation device in the present invention, operators can accurately adjust the fresh water injection volume of the fresh water supply device or the liquid ammonia flow rate input by the liquid ammonia fuel supply device according to the real-time concentration data of ammonia water in the ammonia water preparation device, so as to ensure that the produced ammonia water concentration is always maintained within the optimal working concentration range required by the tail gas denitration device. By providing a liquid level detection device, the liquid level of ammonia water can always be controlled within a safe range, ensuring the safety of use of the ammonia water preparation device.

[0022] In an alternative embodiment, an ammonia water storage tank is further included. The inlet of the ammonia water storage tank is connected to the outlet of the ammonia water preparation device through a first ammonia water delivery pipeline, and the outlet of the ammonia water storage tank is connected to the tail gas denitration device through a second ammonia water delivery pipeline.

[0023] Beneficial effects: By arranging an ammonia water storage tank between the ammonia water preparation device and the tail gas denitration device, the present invention can temporarily store the ammonia water produced by the ammonia water preparation device in the storage tank, buffering the rate difference between ammonia water preparation and denitration use. Specifically, when the ammonia water production rate of the preparation device is fast while the consumption rate of the denitration device is slow, the excess ammonia water can be stored; on the contrary, when the denitration demand surges, the ammonia water stored in the storage tank can be quickly replenished.

[0024] In an alternative embodiment, an ammonia water pump, a second regulating valve and a second flow meter are provided on the second ammonia water conveying pipeline; one end of the second ammonia water conveying pipeline is provided with a second spray head, and the second spray head extends into the interior of the tail gas denitration device.

[0025] Beneficial effects: The ammonia water pump can ensure that the ammonia water can be continuously and smoothly conveyed to the tail gas denitration device, ensuring the uninterrupted progress of the denitration work. The second flow meter can real-time monitor the flow data of the ammonia water. In cooperation with the second regulating valve, the operator can accurately adjust the conveying amount of the ammonia water according to the actual content of nitrogen oxides in the tail gas and the specific requirements of the denitration reaction. When the concentration of nitrogen oxides in the tail gas is high, the second regulating valve is opened wider to increase the ammonia water conveying amount; when the concentration is low, it is correspondingly reduced, realizing precise control, avoiding waste or insufficient supply of ammonia water, reducing the operation cost while improving the denitration efficiency. In addition, extending the second spray head into the interior of the tail gas denitration device can evenly disperse the ammonia water in the form of spraying in the tail gas, increasing the efficiency of ammonia water pyrolysis into ammonia gas, and at the same time increasing the contact area between ammonia gas and nitrogen oxides, enabling the two to fully mix and quickly react, improving the efficiency and effect of the denitration reaction.

[0026] In a second aspect, the present invention also provides a method for denitrifying the tail gas of an ammonia fuel engine, including:

[0027] Collecting the unburned ammonia gas generated in the supply pipeline between the ammonia fuel engine and the liquid ammonia fuel supply device by using an ammonia gas buffer tank;

[0028] Conveying the unburned ammonia gas in the ammonia gas buffer tank and the liquid ammonia in the liquid ammonia fuel supply device to an ammonia water preparation device for preparing ammonia water;

[0029] Conveying the ammonia water in the ammonia water preparation device to a tail gas denitration device for treating the tail gas of the ammonia fuel engine.

[0030] Beneficial effects: The present invention utilizes an ammonia buffer tank to collect the unburned ammonia generated in the supply pipeline, which not only avoids the direct emission of ammonia, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operating cost. Secondly, the collected ammonia is transported to the ammonia water preparation device, enabling the ammonia that might otherwise be wasted or difficult to handle to be converted into ammonia water that is easier to store, transport, and use. The state of ammonia water is relatively stable, reducing the safety risk of subsequent operations. Finally, the prepared ammonia water is transported to the tail gas denitrification device to treat the tail gas of the ammonia fuel engine, effectively removing harmful components such as nitrogen oxides in the tail gas. In addition, since ammonia water can replace the conventional reducing agent urea, the construction of the urea storage tank on the ship can also be cancelled, reducing the occupation of ship space by the reducing agent.

[0031] In an optional embodiment, the ammonia water preparation device includes a washing cabinet, an ammonia water preparation device, and a fresh water supply device connected to the washing cabinet and the ammonia water preparation device. The washing cabinet is connected to the gas outlet of the ammonia buffer tank, and the outlet of the washing cabinet and the outlet of the liquid ammonia fuel supply device are respectively connected to the inlet of the ammonia water preparation device; the unburned ammonia in the ammonia buffer tank and the liquid ammonia in the liquid ammonia fuel supply device are transported to the ammonia water preparation device for preparing ammonia water, and it further includes:

[0032] Transport the unburned ammonia in the ammonia buffer tank into the washing cabinet; transport the liquid ammonia in the liquid ammonia fuel supply device into the ammonia water preparation device;

[0033] Utilize the fresh water supply device to transport fresh water into the washing cabinet to prepare a first ammonia water solution; transport the first ammonia water solution into the ammonia water preparation device, and utilize the fresh water supply device to transport fresh water into the ammonia water preparation device to prepare a second ammonia water solution.

[0034] Beneficial effects: The present invention utilizes liquid ammonia and unburned ammonia to jointly prepare ammonia water, enabling operators to flexibly adjust the preparation concentration of ammonia water according to actual needs, ensuring the purification effect of ammonia water on the tail gas of the ammonia fuel engine. Description of the Drawings

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a connection schematic diagram of a tail gas denitrification system for an ammonia fuel engine according to an embodiment of the present invention.

[0037] Description of the reference numerals:

[0038] 1. Ammonia fuel engine; 2. Liquid ammonia fuel supply device; 3. Supply pipeline; 4. Ammonia buffer tank; 5. Ammonia water preparation device; 501. Washing cabinet; 502. Ammonia water preparation equipment; 503. Fresh water supply device; 5031. Fresh water delivery pipeline; 6. Tail gas denitrification device; 7. Ammonia water storage tank; 8. First ammonia water delivery pipeline; 9. Second ammonia water delivery pipeline; 10. Ammonia water pump; 11. Ammonia water concentration detection device; 12. Liquid level detection device. Detailed implementation manners

[0039] For the purpose of making the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The following will be combined with Figure 1 , to describe the embodiments of the present invention.

[0041] According to an embodiment of the present invention, on the one hand, as Figure 1 shown, a tail gas denitrification system for an ammonia fuel engine is provided, including: an ammonia fuel engine 1, a liquid ammonia fuel supply device 2, an ammonia buffer tank 4, an ammonia water preparation device 5, and a tail gas denitrification device 6.

[0042] Specifically, the liquid ammonia fuel supply device 2 is connected to the ammonia fuel engine 1 through the supply pipeline 3 for supplying ammonia fuel to the ammonia fuel engine 1; the inlet of the ammonia buffer tank 4 is connected to the supply pipeline 3 for collecting the unburned ammonia gas generated in the supply pipeline 3; the ammonia water preparation device 5 is connected to the outlet of the ammonia buffer tank 4 and the outlet of the liquid ammonia fuel supply device 2; the tail gas denitrification device 6 is connected to the outlet of the ammonia water preparation device 5 and the exhaust port of the ammonia fuel engine 1.

[0043] In the embodiment of the present invention, the ammonia buffer tank 4 is used to collect the unburned ammonia generated in the supply pipeline 3. This not only avoids the direct emission of ammonia, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operating cost. Secondly, the unburned ammonia is transported to the ammonia water preparation device 5, converting the ammonia that might otherwise be wasted or difficult to handle into ammonia water that is easier to store, transport, and use. The state of ammonia water is relatively stable, reducing the safety risks of subsequent operations. Furthermore, a part of the liquid ammonia in the liquid ammonia fuel supply device 2 is directly transported to the ammonia water preparation device 5, enabling the operator to flexibly adjust the preparation concentration of ammonia water according to actual needs, ensuring the purification effect of ammonia water on the exhaust gas of the ammonia fuel engine. Finally, the prepared ammonia water is transported to the tail gas denitration device 6 to treat the exhaust gas of the ammonia fuel engine. This can not only effectively remove harmful components such as nitrogen oxides in the exhaust gas, but also reduce the consumption of the original reducing agent, improving economic efficiency. In addition, since ammonia water can replace the conventional reducing agent urea, the construction of the urea storage tank on the ship can also be cancelled, reducing the occupation of ship space by the reducing agent.

[0044] It should be noted that the unburned ammonia referred to in this embodiment actually refers to the ammonia formed by the evaporation of part of the liquid ammonia under the influence of the pressure difference during the process of the liquid ammonia fuel supply device 2 transporting liquid ammonia to the ammonia fuel engine 1 through the supply pipeline 3. In addition, the reason for not directly connecting the ammonia water preparation device 5 to the supply pipeline 3 is that the pressure of the liquid ammonia in the liquid ammonia fuel supply device 2 is relatively high. Therefore, by setting the ammonia buffer tank 4 between the supply pipeline 3 and the ammonia water preparation device 5, the ammonia pressure input into the ammonia water preparation device 5 can be reduced, avoiding damage to the ammonia water preparation device 5.

[0045] According to an embodiment of the present invention, as Figure 1 shown, the ammonia water preparation device 5 includes a washing cabinet 501, an ammonia water preparation equipment 502, and a fresh water supply device 503 connected to the washing cabinet 501 and the ammonia water preparation equipment 502. The washing cabinet 501 is connected to the gas outlet of the ammonia buffer tank 4. The outlet of the washing cabinet 501 and the outlet of the liquid ammonia fuel supply device 2 are respectively connected to the inlet of the ammonia water preparation equipment 502. The outlet of the ammonia water preparation equipment 502 is connected to the tail gas denitration device 6. In the embodiment of the present invention, both ammonia and fresh water are transported into the washing cabinet 501, enabling the ammonia to react with the fresh water to obtain ammonia water. Compared with ammonia, when ammonia is converted into ammonia water, its state is relatively more stable, so it can be transported and stored more conveniently. In addition, transporting fresh water and liquid nitrogen to the ammonia water preparation equipment 502 can increase the final preparation concentration of ammonia water, avoiding the situation where only unburned ammonia is used to prepare ammonia water and cannot meet the reduction requirements of the exhaust gas of the ammonia fuel engine.

[0046] According to an embodiment of the present invention, a reflux port is provided on the bottom and / or side wall of the washing cabinet 501, and a spray port is provided on the top of the washing cabinet 501. The reflux port is connected to the spray port through a reflux pipeline and a reflux pump provided on the reflux pipeline. In the embodiment of the present invention, by providing a reflux port on the bottom and / or side wall of the washing cabinet 501 and a spray port on the top, and connecting the two with a reflux pipeline and a reflux pump, the liquid in the washing cabinet 501 can form a cycle. This cycle process can enable ammonia gas to come into more sufficient contact and reaction with fresh water, thereby increasing the concentration of the prepared ammonia water.

[0047] According to an embodiment of the present invention, the fresh water supply device 503 includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is respectively connected to the washing cabinet 501 and the ammonia water preparation device 502 through a fresh water delivery pipeline 5031. In the embodiment of the present invention, by providing a fresh water pump, the operator can flexibly adjust the amount of fresh water delivered into the washing cabinet 501 and the ammonia water preparation device 502. Specifically, when it is necessary to increase the concentration of ammonia water, the fresh water delivery volume is reduced; if it is necessary to dilute the ammonia water, the delivery volume is increased to ensure that the ammonia water concentration is always maintained within a suitable range.

[0048] According to an embodiment of the present invention, a first spray head is provided inside both the washing cabinet 501 and the ammonia water preparation device 502, and the first spray head is connected to the fresh water delivery pipeline 5031; a first regulating valve and a first flow meter are also provided on the fresh water delivery pipeline 5031. It can be understood that by providing a first spray head inside the washing cabinet 501 and the ammonia water preparation device 502, fresh water can be evenly dispersed in the washing cabinet 501 and the ammonia water preparation device 502 in the form of spraying, increasing the contact area between fresh water and ammonia gas or liquid ammonia, promoting the reaction speed between the two, and improving the production efficiency and quality of ammonia water. By providing a first regulating valve and a first flow meter on the fresh water delivery pipeline 5031, precise quantitative control and dynamic adjustment of fresh water can be achieved, which helps to maintain the stability of the ammonia water concentration in the washing cabinet 501 and ensure that the quality of ammonia water meets the working requirements of the tail gas denitration device 6.

[0049] According to an embodiment of the present invention, as Figure 1As shown, an ammonia water concentration detection device 11 and a liquid level detection device 12 are provided on the ammonia water preparation device 502. The ammonia water concentration detection device 11 is used to detect the concentration of ammonia water in the ammonia water preparation device 502; the liquid level detection device 12 is used to detect the height of the ammonia water liquid level in the ammonia water preparation device 502. In the embodiment of the present invention, by setting the ammonia water concentration detection device 11 on the ammonia water preparation device 502, operators can accurately adjust the fresh water injection volume of the fresh water supply device 503 or the liquid ammonia flow rate input by the liquid ammonia fuel supply device 2 according to the real-time concentration data of the ammonia water in the ammonia water preparation device 502, so as to ensure that the concentration of the produced ammonia water is always maintained within the optimal working concentration range required by the tail gas denitration device 6. And by setting the liquid level detection device 12, the liquid level of the ammonia water can always be controlled within a safe range, ensuring the safety of use of the ammonia water preparation device 502.

[0050] According to an embodiment of the present invention, as Figure 1 shown, it further includes an ammonia water storage tank 7. The inlet of the ammonia water storage tank 7 is connected to the outlet of the ammonia water preparation device 5 through the first ammonia water delivery pipeline 8, and the outlet of the ammonia water storage tank 7 is connected to the tail gas denitration device 6 through the second ammonia water delivery pipeline 9. In the embodiment of the present invention, by setting the ammonia water storage tank 7 between the ammonia water preparation device 5 and the tail gas denitration device 6, the ammonia water produced by the ammonia water preparation device 5 can be temporarily stored in the storage tank, buffering the rate difference between ammonia water preparation and denitration use. Specifically, when the ammonia water production rate of the preparation device is relatively fast and the consumption rate of the denitration device is relatively slow, the excess ammonia water can be stored; conversely, when the denitration demand surges, the ammonia water stored in the storage tank can be quickly replenished.

[0051] According to an embodiment of the present invention, as Figure 1 shown, an ammonia water pump 10, a second regulating valve, and a second flow meter are provided on the second ammonia water delivery pipeline 9; one end of the second ammonia water delivery pipeline 9 is provided with a second spray head, and the second spray head extends into the interior of the tail gas denitration device 6. It can be understood that the ammonia water pump 10 can ensure that the ammonia water can be continuously and smoothly transported to the tail gas denitration device 6, ensuring the uninterrupted progress of the denitration work. And the second flow meter can real-time monitor the flow data of the ammonia water. Cooperating with the second regulating valve, operators can accurately adjust the delivery volume of the ammonia water according to the actual content of nitrogen oxides in the tail gas and the specific requirements of the denitration reaction. When the concentration of nitrogen oxides in the tail gas is relatively high, the second regulating valve is opened wider to increase the ammonia water delivery volume; when the concentration is relatively low, it is correspondingly reduced, achieving precise control, avoiding waste or insufficient supply of ammonia water, reducing the operating cost while improving the denitration efficiency. In addition, by extending the second spray head into the interior of the tail gas denitration device 6, the ammonia water can be evenly dispersed in the tail gas in the form of spraying, increasing the efficiency of the thermal decomposition of ammonia water into ammonia gas, and at the same time increasing the contact area between ammonia gas and nitrogen oxides, enabling the two to fully mix and quickly react, improving the efficiency and effect of the denitration reaction.

[0052] According to an embodiment of the present invention, on the other hand, as Figure 1 shown, a method for denitrifying the exhaust gas of an ammonia fuel engine is provided, including:

[0053] Using an ammonia buffer tank 4 to collect the unburned ammonia generated in the supply pipeline 3 between the ammonia fuel engine 1 and the liquid ammonia fuel supply device 2;

[0054] Transporting the unburned ammonia in the ammonia buffer tank 4 and the liquid ammonia in the liquid ammonia fuel supply device 2 to an ammonia water preparation device 5 for preparing ammonia water;

[0055] Transporting the ammonia water in the ammonia water preparation device 5 to an exhaust gas denitrification device 6 for treating the exhaust gas of the ammonia fuel engine 1.

[0056] In the embodiment of the present invention, the ammonia buffer tank 4 is used to collect the unburned ammonia generated in the supply pipeline 3, which not only avoids the direct emission of ammonia, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operating cost. Secondly, transporting the collected ammonia to the ammonia water preparation device 5 converts the ammonia that might otherwise be wasted or difficult to handle into ammonia water that is easier to store, transport, and use. The ammonia water state is relatively stable, reducing the safety risk of subsequent operations. Finally, transporting the prepared ammonia water to the exhaust gas denitrification device 6 to treat the exhaust gas of the ammonia fuel engine can effectively remove harmful components such as nitrogen oxides in the exhaust gas. In addition, since ammonia water can replace the conventional reducing agent urea, the construction of the urea tank on the ship can also be cancelled, reducing the occupation of the ship's space by the reducing agent.

[0057] According to an embodiment of the present invention, the ammonia water preparation device 5 includes a washing cabinet 501, an ammonia water preparation device 502, and a fresh water supply device 503 connected to the washing cabinet 501 and the ammonia water preparation device 502. The washing cabinet 501 is connected to the air outlet of the ammonia buffer tank 4, and the outlet of the washing cabinet 501 and the outlet of the liquid ammonia fuel supply device 2 are respectively connected to the inlet of the ammonia water preparation device 502; transporting the unburned ammonia in the ammonia buffer tank 4 and the liquid ammonia in the liquid ammonia fuel supply device 2 to the ammonia water preparation device 5 for preparing ammonia water further includes:

[0058] Transporting the unburned ammonia in the ammonia buffer tank 4 into the washing cabinet 501; transporting the liquid ammonia in the liquid ammonia fuel supply device 2 into the ammonia water preparation device 502;

[0059] Using the fresh water supply device 503 to transport fresh water into the washing cabinet 501 to prepare a first ammonia water solution; transporting the first ammonia water solution into the ammonia water preparation device 502, and using the fresh water supply device 503 to transport fresh water into the ammonia water preparation device 502 to prepare a second ammonia water solution.

[0060] In the embodiment of the present invention, ammonia water is prepared by using liquid ammonia and unburned ammonia gas, enabling operators to flexibly adjust the preparation concentration of ammonia water according to actual needs and ensuring the purification effect of ammonia water on the exhaust gas of ammonia fuel engines.

[0061] It can be understood that in this embodiment, the first ammonia water solution refers to a low-concentration ammonia water solution prepared by unburned ammonia gas and fresh water; the second ammonia water solution refers to a higher-concentration ammonia water solution prepared by the first ammonia water solution, liquid ammonia, and fresh water.

[0062] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An ammonia fuel engine exhaust gas denitration system, characterized in that, Comprising: An ammonia fuel engine (1); A liquid ammonia fuel supply device (2), connected to the ammonia fuel engine (1) through a supply pipeline (3), for supplying ammonia fuel to the ammonia fuel engine (1); An ammonia gas buffer tank (4), with its inlet connected to the supply pipeline (3), for collecting unburned ammonia gas generated in the supply pipeline (3); An ammonia water preparation device (5), connected to the outlet of the ammonia gas buffer tank (4) and the outlet of the liquid ammonia fuel supply device (2); An exhaust gas denitrification device (6), connected to the outlet of the ammonia water preparation device (5) and the exhaust port of the ammonia fuel engine (1).

2. The ammonia fuel engine tail gas denitration system according to claim 1, characterized in that, The ammonia water preparation device (5) includes a washing cabinet (501), an ammonia water preparation equipment (502), and a fresh water supply device (503) connected to the washing cabinet (501) and the ammonia water preparation equipment (502). The washing cabinet (501) is connected to the outlet of the ammonia gas buffer tank (4). The outlet of the washing cabinet (501) and the outlet of the liquid ammonia fuel supply device (2) are respectively connected to the inlet of the ammonia water preparation equipment (502). The outlet of the ammonia water preparation equipment (502) is connected to the exhaust gas denitrification device (6).

3. The ammonia fuel engine tail gas denitration system according to claim 2, characterized in that, A reflux port is provided on the bottom and / or side wall of the washing cabinet (501). A spray port is provided at the top of the washing cabinet (501). The reflux port is connected to the spray port through a reflux pipeline and a reflux pump provided on the reflux pipeline.

4. The ammonia fuel engine tail gas denitration system according to claim 2, characterized in that, The fresh water supply device (503) includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is respectively connected to the washing cabinet (501) and the ammonia water preparation equipment (502) through a fresh water delivery pipeline (5031).

5. The ammonia fuel engine tail gas denitration system according to claim 4, characterized in that, First spray heads are provided inside both the washing cabinet (501) and the ammonia water preparation equipment (502). The first spray heads are communicated with the fresh water delivery pipeline (5031). A first regulating valve and a first flow meter are also provided on the fresh water delivery pipeline (5031).

6. The ammonia fuel engine tail gas denitrification system according to claim 2, characterized in that, An ammonia water concentration detection device (11) and a liquid level detection device (12) are provided on the ammonia water preparation equipment (502). The ammonia water concentration detection device (11) is used to detect the ammonia water concentration inside the ammonia water preparation equipment (502). The liquid level detection device (12) is used to detect the height of the ammonia water liquid level inside the ammonia water preparation equipment (502).

7. The ammonia fuel engine exhaust gas denitration system according to any one of claims 1 to 6, characterized in that, An ammonia water storage tank (7) is further included. The inlet of the ammonia water storage tank (7) is connected to the outlet of the ammonia water preparation device (5) through a first ammonia water delivery pipeline (8). The outlet of the ammonia water storage tank (7) is connected to the exhaust gas denitrification device (6) through a second ammonia water delivery pipeline (9).

8. The ammonia fuel engine tail gas denitration system according to claim 7, characterized in that, An ammonia water pump (10), a second regulating valve, and a second flow meter are provided on the second ammonia water delivery pipeline (9). A second spray head is provided at one end of the second ammonia water delivery pipeline (9). The second spray head extends into the interior of the exhaust gas denitrification device (6).

9. A method for denitrifying the exhaust gas of an ammonia fuel engine, characterized in that, Comprising: An ammonia buffer tank (4) is used to collect unburned ammonia gas generated in a supply pipeline (3) between an ammonia fuel engine (1) and a liquid ammonia fuel supply device (2); The unburned ammonia gas in the ammonia buffer tank (4) and the liquid ammonia in the liquid ammonia fuel supply device (2) are transported to an ammonia water preparation device (5) for preparing ammonia water; The ammonia water in the ammonia water preparation device (5) is transported to a tail gas denitrification device (6) for treating the tail gas of the ammonia fuel engine (1).

10. The method for denitrifying ammonia fuel engine exhaust gas according to claim 9, characterized in that, The ammonia water preparation device (5) includes a washing cabinet (501), an ammonia water preparation equipment (502), and a fresh water supply device (503) connected to the washing cabinet (501) and the ammonia water preparation equipment (502). The washing cabinet (501) is connected to the air outlet of the ammonia buffer tank (4), and the outlet of the washing cabinet (501) and the outlet of the liquid ammonia fuel supply device (2) are respectively connected to the inlet of the ammonia water preparation equipment (502); transporting the unburned ammonia gas in the ammonia buffer tank (4) and the liquid ammonia in the liquid ammonia fuel supply device (2) to the ammonia water preparation device (5) for preparing ammonia water further includes: Transporting the unburned ammonia gas in the ammonia buffer tank (4) into the washing cabinet (501); transporting the liquid ammonia in the liquid ammonia fuel supply device (2) into the ammonia water preparation equipment (502); Using the fresh water supply device (503) to transport fresh water into the washing cabinet (501) to prepare a first ammonia water solution; transporting the first ammonia water solution into the ammonia water preparation equipment (502), and using the fresh water supply device (503) to transport fresh water into the ammonia water preparation equipment (502) to prepare a second ammonia water solution.

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